Water Antoine vapor pressure

Example 4.5 2-Propanol (isopropanol) and water form an azeotropic mixture at a particular liquid composition that results in the vapor and liquid compositions being equal. Vapor-liquid equilibrium for 2-propanol-water mixtures can be predicted by the Wilson equation. Vapor pressure coefficients in bar with temperature in Kelvin for the Antoine equation are given in Table 4.113. Data for the Wilson equation are given in Table 4.126. Assume the gas constant R = 8.3145 kJ-kmol 1-K 1. Determine the azeotropic composition at 1 atm. 

B. Example Calculation The Antoine Equation for Water. Table V. l lisls the vapor pressure dalu for water from 20 to 80°C. Values of au, ba, and c0 are calculated from the data at 20, 50, and 80°C by solving the following three simultaneous equations ... 

Toluene 1) and water(2) are essentially immiscible as liquids. Determine the dew-point temperatures and the compositions of the first drops of liquid formed when vapor mixtures of these species with mole fraction i, = 0.23 and r, = 0.77 are cooled at the constant pressure of 101.33 kPa. What is the bubble-point temperature and the composition of the last drop of vapor in each case The vapor pressure of toluene is given by the Antoine equation ... 

Cox Chart Vapor Pressure Plots Vapor Pressure of Water Antoine Equation Constants... 

Vapor pressure The pressure at which pure liquid A can coexist with its vapor at a given temperature. In this text, vapor pressures can be determined from tabulated data (e.g,. Tables B.3 and B.5-B.7 for water), the Antoine equation (Table B.4), or the Cox chart (Figure 6.1-4). 

Values for Antoine coefficients for the air-water system are given in Table 12-3. The standard values give vapor pressure within 0.1 percent of steam tables over the range 50 to 100°C, but an error of nearly 3 percent at 0°C. The alternative coefficients give a close fit at 0 and 100°C and an error of less than 1.2 percent over the intervening range. 

Fig. 1 Vapor pressure of water and 1-alcohols calculated from Antoine equation. (View this art in color at www. dekker.com.)...

CO, mole fraction of 0.01 in the liquid. Calculate the composition of the vapor at equilibrium with the liquid, the vessel pressure, and the /(-values of water and CO,. Henry s law constant for C(), in water at 20°C is 140,000 kPa and the vapor pressure of water is given by the Antoine equation. 

Raoult s law is applied to the water and Henry s law to the CO,. The water vapor pressure at 20 C is calculated from the Antoine equation ... 

Application of Equation (12.48) with the Antoine equation [Equation (12.13)] shows that steam distillation can be used to distill an organic compound at much lower temperatures than would otherwise be possible. Considering the system pressure P as constant, then the more steam introduced, the lower will be the partial and vapor pressures of the organic and thus the lower its boiling point. The other key element of the choice of water as the entrainer is that it is easily separated from the product (organic) by simple condensation followed by decanting. 

In order to solve equations (2-78) and (2-79), expressions for the vapor pressure and latent heat of vaporization of water as a function of temperature are needed. Use the Antoine equation for the vapor pressure (Smith et al., 1996)... 

The ideal gas law characterizes the relationship between pressure, temperature, and volume for gases. Both the Clausius-Clapeyron and Antoine equations characterize the vapor-liquid equilibrium of pure components and mixtures. At atmospheric pressure and ambient temperature, water is a liquid but an equilibrium exists with its vapor phase concentration—its vapor pressure. The vapor pressure is a function of temperature. The formula for the Clausius-Clapeyron equation is ... 

Solution 5.1b. In the case of placing an organic fluid in the cylindrical body of the thermometer immersed in the water, two factors affect the pressure gauge reading the expansion of the air as well as the increased vapor pressure of the organic fluid. The vapor pressure of the fluid is calculated according to Antoine s equation, while the overall pressure is determined from the ideal gas law. Amontons law is inapplicable because the total number of moles of gas in the vapor phase of the cylinder will increase. (We shall also assume that the change in volume of the liquid is inconsequential.)... 

Three moles of benzene, four moles of acetonitrile, and four moles of water are placed in a closed vessel and brought into VLLE at 333 K, 0.70 bar. Assume the liquid phases obey the NRTL equations (Appendix J), with parameter values given in Table J.l. Appendix D contains Antoine parameters for vapor pressures of the pure-components. Use the double Rachford-Rice algorithm of Figure 11.6 to determine the following ... 

At ambient conditions, binary liquid mixtures of ethyl acetate(l) and water(2) are partially miscible. At 343.15 K determine the pressure at which this binary exhibits three-phase VLLE and find the compositions of the three phases. The pure-component vapor pressures can be modeled by an Antoine equation with parameters in Table 11.9. Perform the calculation twice ... 

Antoine equation for vapor pressure of water Oswin equation for material isotherms Drying kinetics equation Belt driver power equation Pressure loss equation... 

The water vapor pressure at temperature can be obtained from the Antoine equation... 

Let the water surface in the tank be adjusted at temperature value and assume a diy air flow ( air n I in = 0) ciiculatuig along the surface, dowly enough that the vapor flow leaving the tank is fully saturated with water. The pressure inside the tank is p. The vapor pressure of the water can be expressed by tbs Antoine equation (Fig. 4.2-7) ... 

Vapor pressure data for water are given in Problem 8.D10. This data can be fit to an Antoine equation form with C = 273.16. The vapor pressure of 1-octanol is predicted by the Antoine equation ... 

Calculate the percentages of methanol and ethanol removed from 200 g feed, when 10 g of the distillate is withdrawn. For the calculation the modified UNIFAC method should be applied. The constants for the Antoine equation for ethanol and water can directly be taken from Figure 5.30. For methanol the vapor pressure constants and the molar mass are given in Appendix A. For the calculation ideal vapor phase behavior should be assumed. 

For this purpose, the values obtained from the vapor pressure equations for both components are multiplied with a factor which is specific for each dataset If the Antoine equation is used, this can be achieved by simply changing the parameter A in Eq. 3.30. The solid line in Figure F.8 shows that the correct slope of the bubble point line can be represented. The water activity coefficient at infinite... 

Once we have defined the function, we can just introduce any equation, conditional or loop, that helps in our calculations. A simple example in Figure 3.5 shows how to build a function to estimate vapor pressure of water from the Antoine equation ... 

When spraying solutions of substances of low molecular weight, a first drying step occurs above the solubility limit of the solute, and the drop reduces in size until the solubility limit is reached. For this first step, which is usually called the first or constant rate period (CRP), the drying velocity, that is, the solvent mass evaporated per unit time, is given by the vapor pressure of the solution at the drop surface, p s, and the vapor pressure in the vicinity of the particle, pv.oo. The vapor pressure at the surface depends - assuming a well-mixed state within the droplet - on the drop temperature and on the water activity within the solution. The surface temperature remains low in the CRP as the solvent, due to its heat of evaporation Ah uses up the sensible heat (expressed by the specific heat capacity Cp of the air-vapor mixture) transferred to the particle by the gas in a hot atmosphere. The particle surface temperature Ts is more or less close to the wet bulb temperature of pure water, depending on the water activity in the case of dissolved matter (see Eq. 5.44 in Volume 1 of this series). The dependence of the vapor pressure of the solvent on the surface temperature Ts may be expressed by the Antoine or Clausius-Clapeyron equation, as... 

Gas mixtures often have moisture. When such a gas mixture is contacted with a porous inorganic adsorbent material or membrane, water vapor may condense in the pores. If gas mixture adsorption or permeation was the objective, condensed water vapor will be a hindrance. A porous inorganic material has pores of 5 nm radius and the temperature of contacting is 25 °C. Water vapor pressure at a temperature T°P can be determined from the Antoine equation (Henley and Seader, 1981) ... 

The swelling strain based on ideal mixing and the real swelling strain are plotted together as functions of water activity in Fig. 3. The curves are almost super-posable. Also there is no discemable difference in the water sorption at different temperatures at the same water activity water sorption increases exponentially with the same temperature dependence as the water vapor pressure [e.g., given by the Antoine equation (3)]. 

In Example 5.3, we used the C-C equation to estimate the vapor pressure of water at 1155.2°R, and compared the calculated value to the steam table value. Repeat that example using the Antoine equation (Eq. 5.14) and the constants in Table A.2. 

Estimate the vapor pressure of subcooled water at this temperature using the Antoine equation and the constants in Table A.2. 

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